The actor is ideal for Avery in the same way that served him well on Kathryn Bigelow's "The Hurt Locker" -- he's got an all-American brand of vague intensity that lends itself to true crime. Renner is entirely watchable, and he's good at playing sketchy characters who can go either way.
Sure, Galifianakis is more court jester than backwoods killer, but a part like Steven Avery is precisely what a funnyman like Zach needs to nail dramatic crossovers. Not to mention the impressive grizzly beard Galifianakis is capable of growing, an Avery hallmark.
Jackson's enjoying a bit of a renaissance thanks to Showtime's "The Affair," in which he plays a jilted husband more than comfortable with murderous intrigue. Jackson is a pretty boy but with the right motivation -- perhaps Avery's 18-year sentence for a rape he was wrongfully convicted of, only to be released and then convicted of murder under similarly suspicious circumstances -- Jackson could really shine.
The same rules apply for "Eastbound and Down"'s McBride as they did for Galifianakis, though McBride has a competitive edge: comfort with depravity. McBride's excessively blunt comedy could translate to a really interesting take on Avery and his supposed violent crimes and demeanor.
Hill is no stranger to a biopic these days, and might find a really sweet spot between simplicity (Avery was said to have an IQ of 70) and duplicity (Avery was a doting and loving father of twin boys who allegedly burned the remains of Teresa Halback carelessly in a fire pit).